[PATCH synaptics] Fix st->mt scaling

[Leon Shaw]

From: Leon Shaw <shaw.leon at gmail.com>

Signed-off-by: Leon Shaw <shaw.leon at gmail.com>
---
 src/eventcomm.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/eventcomm.c b/src/eventcomm.c
index 28d034f..2d03743 100644
--- a/src/eventcomm.c
+++ b/src/eventcomm.c
@@ -71,7 +71,7 @@ struct eventcomm_proto_data
      * exists for readability of the code.
      */
     BOOL need_grab;
-    int st_to_mt_offset[2];
+    int st_min[2];
     double st_to_mt_scale[2];
 #ifdef HAVE_MULTITOUCH
     struct mtdev *mtdev;
@@ -396,6 +396,8 @@ event_query_axis_ranges(InputInfoPtr pInfo)
     event_get_abs(pInfo, pInfo->fd, ABS_Y, &priv->miny, &priv->maxy,
 		  &priv->synpara.hyst_y, &priv->resy);
 
+    proto_data->st_min[0] = priv->minx;
+    proto_data->st_min[1] = priv->miny;
     priv->has_pressure = FALSE;
     priv->has_width = FALSE;
     SYSCALL(rc = ioctl(pInfo->fd, EVIOCGBIT(EV_ABS, sizeof(absbits)), absbits));
@@ -429,10 +431,8 @@ event_query_axis_ranges(InputInfoPtr pInfo)
         event_get_abs(pInfo, pInfo->fd, ABS_MT_POSITION_Y, &priv->miny,
                       &priv->maxy, &priv->synpara.hyst_y, &priv->resy);
 
-        proto_data->st_to_mt_offset[0] = priv->minx - st_minx;
         proto_data->st_to_mt_scale[0] =
             (priv->maxx - priv->minx) / (st_maxx - st_minx);
-        proto_data->st_to_mt_offset[1] = priv->miny - st_miny;
         proto_data->st_to_mt_scale[1] =
             (priv->maxy - priv->miny) / (st_maxy - st_miny);
     }
@@ -641,9 +641,11 @@ static int count_fingers(InputInfoPtr pInfo, const struct CommData *comm)
 
 
 static inline double
-apply_st_scaling(struct eventcomm_proto_data *proto_data, int value, int axis)
+apply_st_scaling(SynapticsPrivate *priv, int value, int axis)
 {
-    return value * proto_data->st_to_mt_scale[axis] + proto_data->st_to_mt_offset[axis];
+    struct eventcomm_proto_data *proto_data = priv->proto_data;
+    return (value - proto_data->st_min[axis]) * proto_data->st_to_mt_scale[axis] +
+                (axis ? priv->miny : priv->minx);
 }
 
 Bool
@@ -738,10 +740,10 @@ EventReadHwState(InputInfoPtr pInfo,
 	    if (ev.code < ABS_MT_SLOT) {
 		switch (ev.code) {
 		case ABS_X:
-		    hw->x = apply_st_scaling(proto_data, ev.value, 0);
+		    hw->x = apply_st_scaling(priv, ev.value, 0);
 		    break;
 		case ABS_Y:
-		    hw->y = apply_st_scaling(proto_data, ev.value, 1);
+		    hw->y = apply_st_scaling(priv, ev.value, 1);
 		    break;
 		case ABS_PRESSURE:
 		    hw->z = ev.value;
-- 
1.7.9.5